Leszek Borysiewicz has been the Chief Executive of the Medical Research Council since October 2007. After qualifying from the Welsh National School of Medicine in 1975, he held clinical appointments in South Wales and the Hammersmith Hospital, specialising in Infectious Diseases.  He was then a Lister Research Fellow and a Wellcome Trust Senior Lecturer at the Royal Postgraduate Medical School.  In 1988 he was appointed Lecturer in Medicine at the University of Cambridge and then returned to Cardiff as Professor of Medicine from 1991 to 2001.  His research has focussed on the host response to human persistent virus infections notably with cytomegalovirus and papillomavirus.  This led to therapeutic vaccine candidates against cervical cancer.  In 2001 he was appointed Head of the Faculty of Medicine at Imperial College and became Deputy Rector of Imperial College in 2004.  

He has held a number of other posts including Governor of the Wellcome Trust, Chair of the Research Assessment Exercise Main Panel for Medicine, Council Member of Cancer Research UK, Chair of the Molecular and Cell Board and MRC Council Member and Chair of the Science Council of the International Agency for Cancer Research in Lyons.  He was knighted in 2001 for services to medical research and education, is a founding Fellow of the Academy of Medical Sciences and was elected a Fellow of the Royal Society in 2008.

Leszek was born in Cardiff of Polish parents.  His wife, Gwenllian is a general practitioner and they have two daughters. He lives in Ealing, West London.